Yellow mustard is one of the major crops in Western Canada. Commercially, yellow mustard seeds are processed into condiments and other food ingredients (Sharafabadi, 1990) while the bran by-product has little commercial value. The brans are rich in water-soluble mucilaginous material deposited on the outer layer of the testa (Sidiqui et al., 1986). Yellow mustard mucilage is composed of water-soluble polysaccharides containing two major fractions: a cellulose-like neutral polysaccharide fraction and a pectic-like acidic polysaccharide fraction (Cui et al., 1993b, 1994a, 1995a,b).
Earlier publications revealed that yellow mustard mucilage extracted from whole seed exhibited unique rheological properties in aqueous systems and excellent emulsion capacity and stability in oil/water systems (Cui et al., 1993a, 1994b). These properties are desirable for making yellow mustard mucilage commercially viable as a hydrocolloid gum for food and non-food applications. Preliminary studies indicated that 30-40% of the bran could be extracted as gum although the rheological properties of the extracted gum varied with extraction conditions.
The extracted yellow mustard gum exhibited rheological properties giving it the ability to interact with galactomannans synergistically (Cui, et al., 1995c).
U.S. Pat. No. 4,980,186 issued to Sharafabadi discloses a process for extracting yellow mustard gum. The process is a water extraction and is time-temperature dependent. The patent teaches that the resulting gum composition depends to some extent on the extraction process. The particular process used to extract the gum may change some of the rheological properties of the gum and therefore influence its suitability for use in certain products.
Sharafabadi teaches that the whole seed is treated with water in a first step and then the water extract is separated from the seed. The yellow mustard gum is contained in the water extract and may be precipitated using a number of well known methods. Sharafabadi teaches a broad temperature range for extraction in the range of 55-100.degree. C. and a water:seed ratio which must be in the range of 2:1-7:1 for the 17 hour extraction in order for the extraction to be effective. Sharafabadi obtains approximately 4% yield of gum after 4-5 multiple extractions extending over approximately 17 hours (as compared to 5.3% yield reported by Cui 1993a which represents an incomplete extraction of mucilage from whole mustard seeds). This extraction has the disadvantage of requiring large amounts of water to satisfy the water:seed ratio. As well, this large amount of water is boiled during the extraction process and therefore is a very energy demanding process to obtain a small yield of mucilage. As well, due to the extended extraction time necessary for this process, Sharafabadi added a small amount of chloroform to prevent microbial fermentation. Chloroform is a known carcinogen and it is not desirable to use it in any product for internal or external use by individuals.
It is therefore desirable to provide for a process to extract yellow mustard gum over a shorter time period and more economically. It is also desirable to provide for an improved extraction process resulting in a high yield of yellow mustard gum having unique rheological properties.
It is also desirable to provide for yellow mustard gum which is able to interact with galactomannans improving the viscosity and gel structure for use in products applicable to skin.